http://www.wsj.com/articles/a-first-look-at-americas-supergun-1464359194
DAHLGREN, Va.—A warning siren bellowed through the concrete bunker of a top-secret Naval facility where U.S. military engineers prepared to demonstrate a weapon for which there is little defense.
Officials huddled at a video screen for a first look at a deadly new supergun that can fire a 25-pound projectile through seven steel plates and leave a 5-inch hole.
The weapon is called a railgun and requires neither gunpowder nor explosive. It is powered by electromagnetic rails that accelerate a hardened projectile to staggering velocity—a battlefield meteorite with the power to one day transform military strategy, say supporters, and keep the U.S. ahead of advancing Russian and Chinese weaponry.
Sounds like they're thinking of using railguns for a lot of different purposes:
“I can’t conceive of a future where we would replicate Cold War forces in Europe,” said Deputy Secretary of Defense Robert Work, one of the weapon’s chief boosters. “But I could conceive of a set of railguns that would be inexpensive but would have enormous deterrent value. They would have value against airplanes, missiles, tanks, almost anything.”